Absorption refrigeration apparatus



Nov. 22, 1960 w. G. KOGEL ABSORPTION REFRIGERATION APPARATUS 2 Sheets-Sheet 1 Filed Oct. 27, 1958 554:1 BY if-M r I 39/ 38 36 AATTO/P/VE) Nov. 22, 1960 w. G. KOGEL 2,960,846

ABSORPTION REFRIGERATION APPARATUS Filed Oct. 27, 1958 2 Sheets-Sheet 2 i 24 1 ill INVENTOR.

muzafi w BY QM United States Patent ABSORPTION REFRIGERATION APPARATUS Wilhelm Georg Kogel, Stockholm, Sweden, assignor to Aktiebolaget Electrolux, Stockholm, Sweden, 2 corporation of Sweden My invention relates to absorption refrigeration apparatus of the kind in which vapor is expelled out of solution by heating.

It is an object of my invention to provide for absorption refrigeration apparatus of this type an improved heating structure which is suitable for operation with a fluid fuel burner and is of simplified construction and requires a minimum number of parts.

Another object of my invention is to provide for a vapor-expulsion unit of absorption refrigeration apparatus of this type improved heating structure which is suitable for operation with a fluid fuel burner and includes as a component part thereof a heater member which also can be efficiently employed as a component part of another form of heating structure suitable for electrical operation.

The invention, together with the above and other objects and advantages thereof, will be more fully un derstood upon reference to the following description and accompanying drawing forming a part of this specification, 'of which:

Fig. 1 illustrates more or less diagrammatically absorption refrigeration apparatus provided with heating structure which embodies my invention and is adapted to be employed with a fluid fuel burner;

Fig. 2 is an enlarged fragmentary view of parts of the refrigeration apparatus shown in Fig. 1 provided with heating structure adapted to be employed with an electrical heating element;

Fig. 3 is an enlarged fragmentary view of parts shown in Fig. 1 to illustrate details more clearly; and

Fig. 4 is a fragmentary horizontal sectional view taken at line 4-4 of Fig. 3.

Referring to Fig. 1, I have shown my invention embodied in an absorption refrigeration system of a uniform pressure type in which an inert pressure equalizing gas is employed. A refrigeration system of this type comprises a vapor-expulsion unit containing a refrigerant, such as ammonia, in solution in a body of absorption liquid, such as water. Heat is supplied to the vapor-expulsion unit 10 from a heating ,tube 11: in

a manner to' be described presently. Let us assume that the refrigeration system of Fig. l is provided with heating structure like that illustrated in Fig. 2 in which the heating tube 11 is arranged to be heated by an electrical heating element 12 disposed within the tube.

The heat supplied to the vapor expulsion unit and absorption solution contained therein expels refrigerant vapor out of solution, and, in a manner which will be described hereinafter, the refrigerant vapor passes upwardly from the vapor-expulsion unit 10 through a vapor supply line or conduit 14 and an air-cooled rectifier 15 into an air-cooled condenser 16 in which it is condensed and liquefied. Liquid refrigerant flows from condenser 16 through a conduit 17 into a cooling element 18 in which it evaporates and diffuses into an inert pressure equalizing gas, such as hydrogen, which enters through a conduit 19. Due to evaporation of refrigerant fluid into inert gas in cooling element 18, a refrigerating effect is produced with consequent absorption of heat from the surroundings.

The rich gas mixture of refrigerant vapor and inert gas formed in cooling element 18 flows from the lower part thereof through one passage of a gas heat exchanger 20, a conduit 21 and an absorber vessel 22 into the lower end of an absorber coil 23. In absorber coil 23 the rich gas mixture flows counter-current to downwardly flowing absorption liquid which enters through a conduit 24. The absorption liquid absorbs refrigerant vapor from inert gas and inert gas weak in refrigerant flows from absorber coil 23 in a path of flow including a conduit 25, another passage of gas heat exchanger 20 and conduit 19 into the upper part of cooling element 18. Absorption solution enriched in refrigerant flows from the absorber vessel 22 through a conduit 26, an inner passage of a liquid heat exchanger 27 and a connection 28 into a vertically extending pipe 29 at a point 30 which is at a level below the liquid surface level of the body of liquid held in the absorber vessel 22. The extreme lower end of pipe 29 is in communication with the lower end of a pump pipe or vapor lift tube 31 in thermal exchange relation with the heating tube 11 at 32, as by welding, for example. The part of the pump or lift pipe 31 in thermal exchange relation with the heating tube 11 may be referred to as the vaporforming part, in which vapor bubbles are formed due to heat derived from the heating tube. Due to the formation of these vapor bubbles which tend to collect and become larger and larger, liquid in the lift pipe 31 becomes segregated, whereby slugs of liquid are caused to rise in the lift pipe by vapor lift action. Upward movement is imparted to liquid in the vapor lift pipe 31 under the influence of a reaction head formed by the liquid column maintained. in pipe 29.

Vapor generated in the vapor lift pipe 31 flows from the upper end thereof through the upper part of standpipe 33 and a conduit 40 to a region 41 in pipe 29 which serves as an analyzer and is disposed below the liquid surface level A of the liquid column contained therein, the liquid level A being essentially the same as the liquid level B in the absorber vessel 22. The absorption liquid introduced into the analyzer 41 is relatively rich in refrigerant and at a lower temperature than the generated vapor, and, in bubbling through the enriched solution, water vapor present in the vapor is cooled sufficiently and condenses and in this way is removed from ammonia vapor.

The absorption liquid from which refrigerant vapor has been expelled flows by gravity from standpipe 33 through the outer passage of liquid heat exchanger 27 and conduit 24 into the upper part of absorbercoil 23.

' of the gas heatexch'anger 20, for example, so that any inert gas which may pass through the condenser 16 can flow to the gas circuit.

The vapor-expulsion unit 10 in its entirety, together with a major portion of the liquid heat exchanger 27, are embedded in a body of insulating material 35 retained in a metal shell or casing 36 having an opening at the bottom thereof. The heating tube 11 is embedded in a part of the body of insulating material 35 which is intermediate the ends thereof and spaced from the top and bottom ends of the shell 36. In Fig. 2 the electrical heating element 12 is arranged to be positioned within the heating tube 11 through a hollow sleeve member 37 which is formed of suitable insulating material and extends from the bottom of the heating tube 11 to the bottom opening in the shell 36.

- the heating element 12 which may comprise a cartridge housing an electrical wire or the like having a relatively high resistance that generates heat when connected to a source of electrical energy.

In accordance with my invention, the heating tube 11 i may be employed as a component part of heating structure adapted to be employed with an electrical heating element, in the manner just described and illustrated in Fig. 2; and also as a component part of heating structure adapted to be employed with a fluid fuel burner in the manner illustrated in Figs. 1, 3 and 4. In Figs. 1, 3 and 4 the heating tube 11 forms an intermediate section olf a flue pipe'42 having a-bottom section 42a which projects through the bottom opening in the shell 36 and a top section 42b which projects through a top opening in the shell 36. The top and bottom flue pipe sections 42b and 42a are of larger cross-sectional area than the heating tube 11 and the ends of these flue pipe sections snugly fit over H the upper and lower ends, respectively, of the heating tube 11. 1

e A suitable gaseous fuel'burner'43, which may be supported in any suitable manner at the bottom end of the flue pipe 42, is provided with a burner head 43a disposed within the bottom flue pipe section 42a. It will be understood that a gap of suitable size is formed between the I burner 43 and bottom flue pipe section 42a to provide 1 a passage for secondary air which will insure complete combustion of the mixture of gaseous fuel and primary 'air discharged from the burner head 43a. head 43a desirably should be positioned within the bot- The burner tom flue pipe section 42a so that the combustion gases will be used most effectively for heating the heating tube In view of the foregoing, it will now be understood that the heating tube 11 of the refrigeration apparatus may be employed as a component part of one form of heating structure suitable for electrical operation and also as a component part of another form of heating structure suitable for gas operation. When refrigeration apparatus like that illustrated in Fig. 1 is intended to be operated electrically, the hollow insulating sleeve 37 is positioned' between the heating tube 11 and bottom'opening 'in the shell 36, as seen in Fig. 2, before the insulating I material 35 is placed within the shell 36. The hollow sleeve 37 provides a passage for inserting the electrical heating element 12 within the heating tube 11. When the refrigeration apparatus is intended to be operated by 4. V a. aa in Figs. 1, 3 and 4 provides an efiicient arrangement for employing a fluid fuel burner to operate the refrigeration apparatus. In this way, asingle production line can be maintained for fabricating refrigeration apparatus which can be used with either form of heating structure suitable for electrical or gas operation.

As best shown in Fig. 2, the length of the heating tube 11 is substantially limited to the length of the welded joint 32 which heat conductively connects the heating tube 11 and pump pipe 31. With both electrical and gas operation, therefore, effective heating of the pump pipe 31 is effected with the heating structures illustrated and described above because in each instance the source of heat, is concentrated on the heating tube '11 and heat losses, that is, heat not effectively given up to the pump pipe 31, are at a minimum.

While I have shown and described a single embodiment of my invention, it will be apparent that modifications and changes may be made Without departing from the spirit and scope of the invention, as pointed out in the following claims.

I claim:

1. In absorption refrigeration apparatus, an upright shell having an upstanding side wall and a top and bottom and insulation therein, a vapor-expulsion unit embedded in the insulation, said vapor-expulsion unit having at least one part in which vapor is expelled from solution by heating, a heating tube which is disposed in said shell and spaced from the top and bottom and also removed from the side wall, means heat conductively connecting the exterior surfaces of said tube and said part along a a line which extends lengthwise of said tube, said heating tube being hollow and adapted to receive an electrical heating element for operating the apparatus electrically,

'. and means for operating the apparatus with a combustible fuel mixture comprising a flue pipe for combustion gases which extends through said shell between the top and bottom thereof, the top and bottom of said shell having openings communicating with the upper and lower ends of said flue pipe, said flue pipe providing a path of flow for combustion gases and comprising top and bottom pipe sections'substantially in alignment and in communication with one another, and said heating tube being interposed between the top and bottom pipe sections and joined 45 thereto and having its inner surface in the path of flow of the combustion gases.

2. Apparatus as set forth in claim 1 which includes a fluid fuel burner having its discharge orifice disposed within said flue pipe at sucha region that the maximum temperature of the combustion gases produced during operation of the burner is developed. along a vertical a gaseous fuel, the flue pipe sections 42a and 42b are posi- 3 tioned overtheopposing ends of the heating tube 11 so that the latter forms an intermediate section of the flue pipe 42.

The form of heating structure illustrated in Fig. 2 provides an eflicient arrangement for employing an electrical heating element to operate the refrigeration apparatus. Similarly, the form of heating structure illustrated L range. of the flue pipe at which said heating tube is inter- :between said top and bottom pipe sections.

. References Cited in the file of this patent UNITED STATES PATENTS 2,795,940 Kogel June 18, 1957 

